Changing the Brush Size

app/src/main/java/com/dragosholban/androiddrawing/DrawingView.java

@@ -17,6 +17,8 @@
     private ArrayList<Path> paths = new ArrayList<>();
     private ArrayList<Integer> colors = new ArrayList<>();
     private int currentColor = 0xFF000000;
+    private ArrayList<Integer> widths = new ArrayList<>();
+    private int currentWidth = 6;
 
     public DrawingView(Context context) {
         super(context);
@@ -38,6 +40,7 @@ public DrawingView(Context context, @Nullable AttributeSet attrs, int defStyleAt
     public void addPath(Path path) {
         paths.add(path);
         colors.add(currentColor);
+        widths.add(currentWidth);
     }
 
     public Path getLastPath() {
@@ -57,7 +60,7 @@ protected void onDraw(Canvas canvas) {
             Paint paint = new Paint();
             paint.setColor(colors.get(i));
             paint.setStyle(Paint.Style.STROKE);
-            paint.setStrokeWidth(3f);
+            paint.setStrokeWidth(widths.get(i));
             canvas.drawPath(path, paint);
             i++;
         }
@@ -66,4 +69,8 @@ protected void onDraw(Canvas canvas) {
     public void setCurrentColor(int color) {
         currentColor = color;
     }
+
+    public void setCurrentWidth(int width) {
+        currentWidth = (width + 1) * 2;
+    }
 }

app/src/main/java/com/dragosholban/androiddrawing/MainActivity.java

@@ -4,10 +4,12 @@
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.View;
+import android.widget.SeekBar;
 
 public class MainActivity extends AppCompatActivity {
 
     DrawingView drawingView;
+    SeekBar seekBar;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -16,6 +18,24 @@ protected void onCreate(Bundle savedInstanceState) {
 
         drawingView = findViewById(R.id.canvas);
         drawingView.setOnTouchListener(new TouchListener());
+
+        seekBar = findViewById(R.id.seekBar);
+        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
+            @Override
+            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
+                drawingView.setCurrentWidth(progress);
+            }
+
+            @Override
+            public void onStartTrackingTouch(SeekBar seekBar) {
+
+            }
+
+            @Override
+            public void onStopTrackingTouch(SeekBar seekBar) {
+
+            }
+        });
     }
 
     public void setColor(View view) {

app/src/main/res/layout/activity_main.xml

@@ -31,7 +31,7 @@
         android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         android:orientation="horizontal"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@+id/seekBar"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent">
         <View
@@ -63,4 +63,16 @@
             android:background="#000000"
             android:onClick="setColor"/>
     </LinearLayout>
+    <SeekBar
+        android:id="@+id/seekBar"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginBottom="8dp"
+        android:layout_marginEnd="8dp"
+        android:layout_marginLeft="8dp"
+        android:layout_marginRight="8dp"
+        android:layout_marginStart="8dp"
+        android:max="9"
+        android:progress="2"
+        app:layout_constraintBottom_toBottomOf="parent" />
 </android.support.constraint.ConstraintLayout>